The present invention is directed to the control of various devices having different codes for controlling their respective functions. In particular, the invention is directed to a system for enabling a single control unit, such as a remote control unit, to control the functions of multiple controllable devices, each of which has its own specific set of control instructions.
One area in which remote control units have gained widespread use and popularity is the field of home entertainment. A typical entertainment system might include such devices as a television, a video cassette recorder (VCR), a cable television decoder and a compact disc player. Each of these devices might be controllable by means of a remote control unit that is supplied with the device. Typically, each controllable device will have a separate remote control unit associated with it.
A standard remote control unit uses an infrared transmitter to communicate with the device to be controlled. When a user presses a key on the unit to instruct the controllable device to perform a certain function, a series of infrared pulses are transmitted to the device. These pulses correspond to a series of logical ones and zeroes which form the control code for the particular command that is being transmitted. An infrared receiver on the controllable device receives these pulses, which are decoded into an instruction signal for the device.
Generally, a remote control unit that is designed for one device is not capable of controlling the functions of another device. For different types of devices, this is usually due to the fact that the functions performed by the two devices are not the same. Thus, for example, the remote control unit for a television is not capable of controlling the playback and record functions of a VCR.
Where they have the same or similar functions, different types of controllable devices will generally employ different respective control codes for their common functions. For example, the control code to instruct a VCR to play a tape may comprise an entirely different format and/or sequence of ones and zeroes than the control code to instruct a compact disc player to play a song on the disc. In this way, the use of a remote control unit for one device will not accidently cause a different device to be activated, against the user's desires.
Furthermore, different manufacturers of the same type of equipment employ different formats and sequences of control codes for their respective devices. Thus, the set of control codes for a VCR from one manufacturer will typically be quite different from the set of control codes for a VCR from another manufacturer, even though both VCRs perform the same functions.
As a result, a different remote control unit is required for each controllable device that may be present in a consumer's home. Where a home entertainment system comprises a number of different devices, it can be appreciated that a number of different remote control units must be present. This situation is cumbersome for the consumer, not only because of the storage problem it presents, but also due to the need to keep track of, and distinguish between, all of the various remote control units.
It is therefore desirable to provide a control unit which is capable of controlling a number of different controllable devices, each of which has its own set of control codes. In the past, two different approaches have been pursued in an effort to provide a universal remote control unit. In one approach, the universal remote control unit includes a memory, typically a read-only memory (ROM), which contains the set of control codes for all known controllable devices, or a specific subset of those devices. The user selects a particular device to be controlled, for example by depressing keys on the remote control unit. In response thereto, the appropriate codes are retrieved from the memory and used to control the device. Examples of this type of universal remote control unit are disclosed, for example, in U.S. Pat. Nos. 4,774,511 (Rumbolt et al) and 4,999,622 (Amano et al).
If this type of unit is to be truly universal in nature, and compatible with all the various types of controllable devices that exist, it will be appreciated that its memory must contain a large number of control codes. Even when data compression techniques are used, the need for a sizable memory can increase the cost, and perhaps also the physical size, of the remote control unit. Even more significantly, however, is the limited applicability of the remote control unit. Since it can only work with those devices whose codes are stored in its ROM, it is not able to accommodate new models that emerge after the encoding of the ROM. Therefore, if the consumer purchases new equipment after having obtained one of these universal remote control units, he likely will not be able to use the remote control unit with the new equipment. In one specific case, a "universal" remote control unit sold by one manufacturer was not able to control the functions of a VCR that was introduced by that same manufacturer only a short while after the sale of the remote control unit.
In an effort to avoid this type of limitation, another approach to universal remote control units involves programming the unit with the codes used by each controllable device of interest. A programmable remote control unit of this type includes an infrared receiver and a programmable memory. To program the unit, the consumer is required to sequentially actuate the original remote control unit that was supplied with the device and the programmable unit. Thus, to program the universal unit to learn the control code associated with the play command for a VCR, for example, the user first presses the play button on the remote control unit that was supplied with the VCR. The programmable remote control unit must be positioned to receive the pulses emitted by the VCR's remote control unit. The play button on the programmable unit is then actuated by the consumer, to thereby inform the programmable unit of the particular command to which the received pulses pertain. This sequence may have to be performed a number of times for each individual command. Examples of this type of a programmable remote control unit are disclosed, for example, in U.S. Pat. Nos. 4,623,877 (Welles), 4,626,848 (Ehlers), 4,802,114 (Sogame) and 4,825,200 (Evans et al).
The need to program the remote control unit in this manner can prove to be cumbersome for the consumer. Typically, the instructions for performing the programming operation are technical in nature and not readily understood by the average lay consumer. In some cases, it may be necessary to obtain code information from an outside source, such as the cable television company, who may be reluctant or unwilling to provide such information. Furthermore, the infrared receiver and programmable memory increase the cost of the unit appreciably.